Environmental risk assessments (ERA) support regulatory decisions
for the commercial cultivation of genetically modified (GM) crops.
The ERA for terrestrial agroecosystems is well-developed, whereas
guidance for ERA of GM crops in aquatic ecosystems is not as
well-defined. The purpose of this document is to demonstrate how
comprehensive problem formulation can be used to develop a
conceptual model and to identify potential exposure pathways, using
Bacillus thuringiensis (Bt) maize as a case study. Within problem
formulation, the insecticidal trait, the crop, the receiving
environment, and protection goals were characterized, and a
conceptual model was developed to identify routes through which
aquatic organisms may be exposed to insecticidal proteins in maize
tissue. Following a tiered approach for exposure assessment,
worst-case exposures were estimated using standardized models, and
factors mitigating exposure were described. Based on exposure
estimates, shredders were identified as the functional group most
likely to be exposed to insecticidal proteins. However, even using
worst-case assumptions, the exposure of shredders to Bt maize was
low and studies supporting the current risk assessments were deemed
adequate. Determining if early tier toxicity studies are necessary
to inform the risk assessment for a specific GM crop should be done
on a case by case basis, and should be guided by thorough problem
formulation and exposure assessment. The processes used to develop
the Bt maize case study are intended to serve as a model for
performing risk assessments on future traits and crops.

Thematic areas

Biosafety policy and regulation

National/Domestic regulatory frameworks or guidelines

National policies

National administrative frameworks

National decision making system

LMO use and transboundary movement

LMOs for introduction into the environment (Environmental releases)

Scientific and technical issues

Risk assessment

Background material to the “Guidance on risk assessment of living modified organisms”

Is this document is recommend as background material for the “Guidance on Risk Assessment of Living Modified Organisms”